Old air in tanks.

[Skipp]

Have not dove for awhile. Last fill of tanks was in August 2015, nitrox. Who would still feel safe diving this air??? Better judgement says to get a vis and refill.

 

[runsongas]

if you analyze it and it matches your last analysis, should be safe to use. degradation would cause the o2 percentage to drop. your call.

 

[DiverDownD3]

At the minimum I would analyze the gas to make sure your O2 level is what it was when it was first analyzed. Oxidation in extreme cases can eat up your oxygen content, so I've heard

 

[Frackingawesome]

Just be sure to shake it. you dont want the O2 to settle at the bottom of the tank... it makes for a rough few first breaths...

 

[Coztick]

Shake it baby, shake it...
Um, what are we shaking?!?

 

[ajduplessis]

Have not dove for awhile. Last fill of tanks was in August 2015, nitrox. Who would still feel safe diving this air??? Better judgement says to get a vis and refill.

Your cylinder is not in date and have been for some time. This alone is good enough reason, at least for me not to dive it. The fact that you had to ask should answer your question, your gut is seldom wrong. Do the basics right or continue with complacency.

Dive Safe

 

[Patoux01]

Your cylinder is not in date and have been for some time. This alone is good enough reason, at least for me not to dive it.

Wait what? Are you thinking it's going to implode when breathing from it?

 

[Steve_C]

O2 settle to the bottom of the tank? Isn't O2 a normal content of air. I can understand how if a tank is topped off the top layer might be a different mix for a while. If O2 will settle out would not the same be true for any other closed container like a room at constant temperature or a 21% mix.. I could be wrong but does not seem right at first thought. The 21% of normal air is just because of the ammount of oxygen earth has available. It is not in any sort of maximum natural ammount as far as I know.

I guess if you are on a low gravity planet that O2 might escape more easily than heaver CO2, but that is not our situation here. Or if we were closer to absolute zero and the molecules quit moving so much O2 might settle out but you cannot breath that temp liquid.

 

[halocline]

I would dive it without any hesitation at all, but I would re-analyze it. That's free and takes less than a minute.

The tank is NOT in violation of any law or even industry standard. It just can't be re-filled without an inspection. If it's an AL tank, oxidation is very very unlikely to be an issue, and the fact that it's nitrox probably decreases the likelihood of a wet fill.

We have some real nervous nellies around here.....it's not like it's prehistoric air found in an ancient tomb.

 

[dberry]

@Steve_C I think you may have missed an invisible smilie on the post about O2 settling to the bottom of the tank.